KSM1 Jabber
*52 tons (47,174 kg) |max accel= *5.7 Seconds (0 to 30 mph) *5.8 Seconds (0 to 30 mph) |engine=Kovac and Sons Morvarc'h Hydrogen Fuel Cell/Electric Motor System, 2,012 hp (1,500 kW) |shield gen=Equipped on select M431A2 MBT models |armor= * Backed Composite Armor *Refractive Coating |sensor= *Active and Passive Radar Systems *Commander's Independent Multiwavelength Viewer *Gunner's Multiwavelength Manual Sight *Driver's Primary Visualization System *Several manual viewports |target=SGD6672 Fire Control Computer |countermeasures= *2 x SGD900 Smoke Grenade Launchers (6 Barrelled) *Inert gas fire suppression systems *SGD Active Protection System |armament= Primary *SGD920A1 Electrothermal-Chemical Smoothbore Cannon, 75 mm L/88 *Surplus Secondary *1 x .50 caliber (12.7 mm) SSA223 Heavy Machine Gun *1 x 7.62 mm (.308 in) SSA107 General Purpose Machine Gun |crew=3 |firstuse= *2537 *2555 |role=Universal Armored Warfare |era= * * |affiliation= *Sironan Miltia * * * }} The KSM1 Jabber (officially KSM1 MBT within the Sironan Militia and M471 MBT across the UNSC) is a main battle tank primarily utilized by the Sironan Militia, though it has also seen limited service within the UNSC Marine Corps and UNSC Army and a handful have fallen into the hands of various Insurrectionist cells. Smaller and less powerfully armed but faster and with theoretically higher levels of protection than the , the KSM1 MBT line was developed by Kovac and Sons Motor Company to specifically face the perceived threats presented by the Covenant while remaining significantly cheaper than its counterpart to fit within the budgetary needs of the Militia. These combined needs are seen by looking at the companies involved with the development of the vehicle. To cut costs, all were smaller, local Sironan companies rather than the larger corporations associated with most UNSC vehicles, such as or . Additionally, the tank and its gun were both smaller and lighter than the Scorpion and its respectively, affording the similar engine power to lead to a significantly more efficient vehicle. Additionally, while potential damage on rounds that managed to penetrate was lessened due to the smaller 75 mm caliber of the gun (further exacerbated by the common usage of self-sharpening sabot rounds), the usage of Electrothermal-chemical propellants allowed for significantly higher and more reliable muzzle velocities, leading to a higher penetration power on the typical rounds fired by the KSM1 compared to the Scorpion. However, this did also lead to a sacrifice when it came to high-explosive rounds and anti-tank missiles fired by the vehicle due to the smaller overall bore size. However, the vehicle performed well enough during the Human-Covenant War that the Sironan Militia took advantage of its increased budget to order an upgrade to the tank in the form of the KSM1A2 (M471A2) Jabber to gradually replace the older model starting in 2555, with the A2 featuring slightly thicker armor overall, an additional coaxial 25 mm M68 Gauss Cannon, and a larger turret. Some select tanks within this later line of Jabbers have also seen the trial integration of shielding technology, though all of these have been within the hands of the UNSC rather than the Sironan Militia. Developmental History Operational History Role and Usage Design Specifications Armament Primary SGD920A1 Smoothbore Cannon ---- The main armament on both the KSM1 and KSM1A2 tanks is the 75 mm SGD920A1 Electrothermal-Chemical Smoothbore Cannon firing primarily a tungsten armor-piercing fin-stabilized discarding sabot round (APFSDS), but also possessing the capability to fire either high-explosive anti-tank (HEAT) or high-explosive squash-head (HESH) rounds, as well as canister shot. This cannon was designed specifically for the KSM1 as part of the original contract by Sironan General Defense, a small, locally founded defense contractor previously known for primarily servicing the needs of the planet's police forces. Due to the small caliber, despite the also small size of the tank, a large number of rounds could be stored, with the KSM1 turret holding 60, the KSM1A2 holding 65, and 15 being located throughout the hull in both models. Finally, the tank could also fire anti-tank guided missiles, with up to five being stored along the Tank Commander's side of the turret, though these could only be manually loaded. Originally planned to be a 7500 mm (100 calibers) gun, the final production model SGD920A1 had to be cut down to 6600 mm (88 calibers) due to issues with production capabilities and turret balance. While testing showed that the reduced barrel length did modestly affect muzzle velocity, the problems with mounting and production capacity proved to be more detrimental than the loss in potential penetration power, with the shorter gun still being able to penetrate analogues to Covenant armor at an acceptable engagement range. The final production cannon had a gun depression of 9 degrees and a gun elevation of 20 degrees when mounted in the KSM1 turret and a gun depression of 10 degrees and gun elevation of up to 22 degrees when mounted in the KSM1A2 turret. Additionally, it possessed an automatic stabilization system that could keep the gun level while driving at maximum velocity over rough terrain with enough precision to reliably hit targets out to its effective range in over 95 percent of cases during testing, with often better results seen during actual combat due to differences in engagement ranges and conditions. The penetrator of the APFSDS round fired by the SGD920A1 comprised of a primarily tungsten alloy 17x395 mm penetrator. While tungsten on its own was considered largely substandard as a tank round by the designers of the vehicle, recent advancements in the years before the Human-Covenant War had led to the discovery of an alloy which possessed both the self-sharpening and incendiary effects of depleted uranium alloy penetrators without the innate toxicity, leading to increased penetration and the chance for potential additional internal damages once the round pierced the target. Combined with the approximately 2,450 meters per second muzzle velocity (just under the hypervelocity threshold) produced by the electrothermal-chemical propellant utilized for the APFSDS rounds for this cannon, the SGD920A1 firing APFSDS rounds could reliably penetrate analogues for Covenant armor out to 4,000 meters, though it has been anecdotally seen success out beyond this range when targetting more lightly armored vehicles. For HE options, the SGD920A1 was provided with both HEAT and HESH rounds, though neither proved reliable against Covenant vehicles. For both, the small caliber and lack of rifling for the bore negatively impacted both explosive potential and accuracy (and subsequently effective range) respectively, though both shell types had the benefit of not losing penetration over distance as the standard APFSDS round would. However, they also proved to be significantly less effective at penetrating Covenant armor than the standard round, with the HESH round getting absorbed by the inherent spaced nature of Covenant armor and the HEAT round just not having enough explosive power behind it to break through the more heavily armored segments. Additionally, the existence of the fourth available shell type, a canister shot, overshadowed the anti-infantry uses of either HE round. As such, the HEAT and HESH rounds primarily saw usage as anti-fortification options, though the HESH performed significantly better for this role than the HEAT did due to the higher proportion of explosive material, leading to most tank crews choosing to take HESH rounds over HEAT rounds whenever they had the opportunity. The final shell option for the SGD920A1 was a canister round. Unlike the canister rounds on the Scorpion, which fired a cylinder containing the eventual shot to be released upon impact, the canister round for the SGD920A1 worked much more like an oversized shotgun, immediately spraying roughly 80 small metal spheres out from the gun's barrel. This was particularly effective against nearby infantry units, though the relatively tight grouping of the shots allowed it to remain reliable out to about 250 meters. Once again, however, the canister round is limited in effectiveness by the smaller caliber of the SGD920A1, leaving the gun unable to fire as many projectiles as the Scorpion's cannon could. In general, while the SGD920A1 offered more penetration and an incendiary effect on its primary armor-piercing round than the Scorpion's main cannon could, it proved to be less effective against fortifications and infantry than the larger tank while also doing less direct internal damage on penetrating hits due to the proportionally smaller projectile as a result of the discarding sabot nature. One of the primary features of the SGD920A1 was its use of an automatic loading system, replacing the need for a fourth crewman in the vehicle. While the tank was still capable of being manually loaded in the event of an autoloader failure, with the breach remaining unblocked by the system when it wasn't in the process of loading a shell, this was considered an unlikely enough situation that the benefits of only having a three-man crew outweighed the possibility that the Tank Commander of Gunner would have to take over loading duties should it occur. To facilitate this emergency manual loading, access to the autoloader's ammunition tray was also available through a manually operated door behind the Tank Commander's seat. The autoloader itself fed through a small opening in the rear of the turret to the ammunition compartment which remained sealed when a round was not currently being fed. This, compared with the door for manual loading, allowed for the ammunition to be separated from the crew-compartment, reducing the risk of crew loss in the case of a direct hit on ammunition when combined with emergency blow-out panels on the top of the turret's ammunition compartment. Within the ammunition compartment, 25 of the turret stowed rounds were available as "ready rounds" on the autoloader's cassette while the remaining rounds were located lower in the turret and would have to be fed onto the autoloader between combat encounters by the Commander through the access hatch. This system allowed more rounds total to be stored in the turret than would otherwise be available if all of them were connected to the autoloader. Additionally, the Gunner had the ability to rotate the cassette to select a particular round as part of the Jabber's fire control system. The autoloader system had a minimum cycle of 4.5 seconds and a maximum cycle of 8 seconds for reload, depending on the current elevation of the gun at the time of being fired. This was due to the autoloader automatically disconnecting from the vertical stabilizer and returning to a level position to line up with the loading tray and rammer. Here, the spent casing was first ejected through an ejection port below the autoloader before the next round was cycled in. While this was occurring, the Gunner could still aim as, while the gun wouldn't respond until the process was complete, the Gunner's firing controls and sight were vertically independent of the gun, dictating where it went, rather than the gun dictating where they aimed. With calculations taking place during the aiming process, the only delay following loading was the gun moving back into position, which took no more than 3.5 seconds. M68 Gauss Cannon ---- The post-war KSM1A2 model of the Jabber also saw a second primary armament mounted coaxially to the right of the SGD920A1 cannon in the form of surplus M68 Gauss Cannons as the UNSC was looking into replacements for the older weapon. While only firing one type of ammunition when used by the Sironan Militia, the M68 became the primary anti-fortification weapon of the post-war Jabber due to the hypervelocity nature of the projectile it fired, with HEAT and HESH rounds not being provided to KSM1A2 Jabbers as a result. While this weapon didn't require any additional development in and of itself, its inclusion in the tank did directly lead to changes for the A2 compared to the original Jabber, primarily in a larger turret, both in width and height, and the incorporation of an additional ammunition compartment to the right of the tank to accommodate the rounds and loading mechanism for the gauss cannon, though the inert nature of the projectiles allowed this one to not be as significantly closed off from the rest of the tank. This compartment could store up to 80 rounds for the M68 on a continuous cassette system, allowing it to automatically reload the weapon. Additionally, the weapon was mounted on its side, with rounds loading into the top and being ejected down a chute contained within the turret towards the bottom right of the tank. Firing 25x130mm high-density projectiles at up to approximately 13,700 meters per second, the M68 Gauss Cannon aimed to take advantage of hypervelocity impacts to damage the targets it hit. Rather than directly penetrating what it impacts, the extreme energies of the collision result in the projectile and its target behaving more like fluids than metals, with both vaporizing upon collision, often in large segments when it comes to the impacted target. These impacts can also often lead to plasma discharges as the air around the area is superheated, often making them easy to mistake as explosions when combined with the similar results they show. While typically utilized in an anti-vehicle role when mounted on Warthogs by the UNSC, this behavior actually led to it being primarily utilized for anti-fortification roles, as the SGD920A1 cannon provided more effective penetration and internal damage to vehicles with its APFSDS rounds while the M68 rounds could provide larger impact craters to leave a bigger hole in static structures. When mounted on the KSM1A2, the M68 Gauss Cannon, by nature of being coaxial with the SGD920A1 cannon, had the same elevation and depression values. However, it fired significantly faster, with only an approximately two-second reload time. Secondary Both models of KSM1 have two machine guns: #A .50 caliber (12.7 mm) SSA223 Heavy Machine Gun on a remote weapons station located on the right side of the top of the turret, just in front of the Commander's hatch, controlled by the Tank Commander. This allows the weapon to be aimed and fired from inside the tank, providing increased protection for the Tank Commander when in a combat situation requiring its utilization. Developed by Sironan Small Arms in the later years of the Insurrection, the SSA223 was similar to the M247H machine gun used by the UNSC, albeit smaller and cheaper. The 223 also had a slower rate of fire (450 RPM) and a shorter effective range than its UNSC counterpart. However, testing by Kovac and Sons Motor Company and the Sironan Militia showed the weapon to be sufficiently effective within the expected infantry engagement ranges of the tank while being provided at a significantly cheaper cost. 750 rounds of ammunition were available for this weapon on the KSM1 and 850 were available on the KSM1A2. #A 7.62 mm (.308 in) SSA107 General Purpose Machine Gun mounted coaxially to the left of the main gun. Much like its bigger sister, the SSA223, the SSA107 was comparable to the standard UNSC M247 machine gun, albeit smaller, cheaper, and with a lessened rate of fire (550 RPM) and a shorter effective range. However, the SSA107's specifications were also found to be within acceptable limits during testing. 4,500 rounds were available for this weapon on the KSM1 and 5,000 were available on the KSM1A2. Aiming All Jabbers are equipped with a ballistic fire-control computer that uses both system and user-supplied data from a variety of sources to compute, display, and incorporate lead angle, range to the target, and selected ammunition type into one single firing solution for the Gunner, allowing the main gun to be fired accurately. Additionally, the Gunner has the option to use the computer to automatically select any of the shell types available in the autoloader cassette to prepare as the next round. Laser rangefinders, crosswind sensors, tracking rate tachometers, and static cant sensors, as well as situational data about shell type-dependent flight characteristics, tank-dependent bore alignment, and a variety of temperature-based effects are all incorporated into the computer's calculations to determine these three factors. This firing solution is updated at over one-hundred times per second and incorporated into the reticle on the Gunner's sight in all modes, allowing the Gunner to reliably hit the target by simply keeping the displayed reticle on it, vastly simplifying his or her job. The Gunner's sight itself can view across a wide range of the electromagnetic spectrum, though the most commonly used settings are thermal and visual. While it is called the "manual sight" in its name, this only refers to the fact that the Gunner has the ability to use it manually, boresighted to the main gun and coaxially weapons, should the targeting system fail, not that he is required to aim manually using it. In fact, the sight is the primary method for the Gunner to aim the weapon even when using the fire-control computer and is the device onto which the targeting reticle is projected. In addition to the Gunner's sight, the Tank Commander can also get an external view of the tank using the Commander's Independent Multiwavelength Viewer (CIMV). This device, with the capabilities to cover the same wide range of the electromagnetic spectrum as the Gunner's sight, allows the Commander to locate targets and pass them on for the gunner to engage while the commander scans for new targets. The CIMV also links with the Commander's Weapon Station to aim and control the remotely operated SSA223 HMG should the need arise. In addition to the two primary target-acquisition systems for the Commander and Gunner to utilize, both also have access to a passive sensor system to detect strong external emission signals that might indicate an enemy out to a maximum range of two kilometers, and the Tank Commander can activate an active air detection radar system to detect incoming aircraft. Armor Primarily designed to fight the Covenant and their plasma weapons, the tank varied from typical defense design in one important manner. While it remained a composite armor system, consisting of layers of Titanium A alloy, open space, plastics, and hardened ceramic blocks, the specific ceramic used was changed. While ceramics generally have the capability to resist high heats, the 3,000°C temperatures reported for some heavy Covenant plasma weapons required something with a higher melting point than the typical silicon carbide. As a result, the decision was made to instead utilize a form of titanium carbide, sintered into coherent plates. While the material was slightly denser and more expensive, the difference that would result in total weight and cost were negligible due to the small size of the Jabber. In turn, the material offered comparable hardness (important for shattering kinetic impactors) and a significantly higher melting point than the alternative, resistant to heat up to over 100°C beyond the highest recorded Covenant plasma temperature. While the armor would still have to deal with the concussive force from direct impacts or near misses from Covenant weaponry, this aspect of the attack was mitigated by the remaining layers of the armor, much like a HEAT shell's blast would be dissipated before making it to the interior of the crew compartment. Another difference in the Jabber's design was the layout of the armor. While it was common to see tanks mount composite armor only on the front of the vehicle's hull and turret, the decision was made to also cover the entire top hull of the Jabber. This was a design choice intended to bolster two factors of the KSM1's intended role: the ability to work within an urban environment and the ability to directly face Covenant forces. For the former factor, the increased armor on the top of the tank served as additional protection against attacks from above. For the latter case, the decision was made specifically to counter indirect fire methods that the Covenant often deployed, specifically from vehicles such as the Wraith or Revenant. In addition, the sides of the turret and the spaced armor skirting placed along the exterior of the Jabber's tracks were both constructed from a composite, though these components made use of the lighter silicon carbide construction to cut down on weight in less vulnerable positions. The remaining faces of the tank's armor consisted of simple Titanium A armor plates, serving only to protect against smaller arms fire, with the decision made to cut down on weight and increase the vehicle's mobility. Upon receiving additional funding in the post-war era, the Sironan Militia up-armored the KSM1A2's larger turret through increasing the thickness of the turret's side armor and implementing silicon-carbide composite armor on the rear. This decision was made following an investigation into the Jabbers that had been knocked out during the Human-Covenant War which had revealed that a large number of Jabbers had been disabled due to Covenant indirect-fire plasma weaponry impacting the rear of the tank, behind the turret. Upon impact, the simple Titanium A plating proved insufficient to disperse the force from the plasma before it could ignite the ammo stored inside, rendering the vehicle inoperable. While the doctrine of the militia to make use of the Jabber's mobility and have it advance under the arch of the incoming plasma and close the gap caused this situation to occur more often, the fact that this doctrine proved successful for Jabbers that avoided such impacts led to the decision to armor the rear of the turret against the plasma, rather than change strategies to something that avoided the hit in the first place. Also making use of the increased post-war funding, the Sironan Militia began upgrading existing KSM1 and new KSM1A2 tanks with slat armor over the rear of the tank's hull. These served to disperse the containment fields of plasma weaponry and decrease their effectiveness before reaching the actual hull of the vehicle without needing to add a significant amount of weight to the design. In addition, tests were conducted into magnetic field generators to actively disrupt these containment fields from a larger distance in a sphere around the entire tank, but these systems did not prove cost-effective and were only implemented on a handful of KSM1A2s before the program was shut down. Countermeasures Mobility Tactical The Jabber comes equipped with the proprietary Kovac and Sons Morvarc'h Hydrogen Fuel Cell/Electric Motor System. This system consists of an array of hydrogen fuel cells found in an isolated compartment to the rear of the tank providing electricity to drive a pair of motors at a combined maximum 2,012 shaft horsepower (1,500 kW) in the constant power range of the motors above 3,000 RPM and a combined maximum torque of 3,522 foot-pounds (4,775 Nm) in the constant torque range below 3,000 RPM. Due to the nature of electric motors, these are connected to the drive wheels at the back of the vehicle's track through a single-speed 10:1 step-down transmission, with reverse managed by electronically triggering the electronic motors to spin backward, driving the tank up to an electronically limited maximum speed of 20 mph (32 km/h). This system is capable of obtaining an electronically limited maximum speed of 50 mph (80 km/h) on paved surfaces falling down to 35 mph (56 km/h) cross-country. While theoretically higher speeds are possible with the electronic limiting system disabled, increased risks of crew injuries, higher maintenance requirements, and the lack of practical use of higher speeds in previous combat situations have seen the limiter remain enabled on the vast majority of KSM1 tanks. While there were originally concerns about the power demands of the tank, with the electronic systems of the vehicle requiring electricity even while the motors aren't running and the motors themselves demanding extensive electrical draws from the fuel cells when they are, the large configuration of fuel cells taking up the rear compartment of the tank covers for this, allowing for a maximum range of approximately 450 miles before requiring refueling, or over three days of continuous idle running of the tank. Additionally, the lack of byproducts except for pure water (collected in a tank beneath the vehicle's fuel cell compartment) allows the tank to operate without an exhaust system, allowing infantry to operate in close proximity to the tank without potential for injury due to high-temperature or high-velocity gas emissions. Furthermore, the electric motors run significantly quieter than traditionally fueled engines while also requiring less maintenance as a whole due to the decreased complexity of the design, lacking automatic transmission fluid and motor oil as well as having generally fewer components as a result. Refueling the Jabber can be done through two methods. The primary method of refueling is to make use of a dedicated refueling facility to pump oxygen and hydrogen directly into the vehicle through a pair of ports to the rear left of the tank. However, if this is unavailable, the Jabber can connect to a wide variety of power sources to directly convert stored water to usable fuel through electrolysis carried out by an internal system connected to the water tank. The port for this connection is located to the rear right of the tank. A portable solar panel system is carried on the majority of Jabbers, capable of generating ten miles worth of fuel an hour on sunny days, designed to provide a method to temporarily refuel a Jabber if it was driven to a standstill without static refueling or power generation stations within range, though this situation proved rare due to the warning issued by the KSM1's fuel management system as the fuel cells came closer and closer to empty. The fuel cell compartment of the KSM1 tank is flooded with an inert gas to counteract the inherent flammability of the fuel cell technology should it get struck by enemy fire. Additionally, this serves to remove the chance of any incident fires sparking as a result of the high temperatures (150 to 200 degrees F) that the fuel cell array operates at. This excess heat is radiated mostly through the rear bottom of the tank, allowing the temperature of the resultant heated air to decrease significantly before reaching a point where it could potentially cause injury to accompanying infantry or the tank crew itself. While the fuel cell array itself has a continuous operation lifetime over up to 50,000 hours, the mileage lifespan of the electric motors is more commonly the limiting factor determining when a Jabber's power system requires maintenance, repair, or replacement, typically only offering a lifespan of just over 30,000 miles. Finally, although the KSM1 is not designed to easily carry riders in the same way the Scorpion was, with the upper rear of the tank's hull being not only small but also often uncomfortably hot due to the operating temperatures of the hydrogen fuel cell system, (even accounting for the directional cooling system) provisions can be made to allow the Jabber to carry a small number of infantrymen in tank desant. This is achieved by locking the turret forward and utilizing ropes and equipment straps to provide handholds on the flat front upper hull of the tank. However, Sironan Militia doctrine does not recommend this strategy due to the exposed position it places the infantry in and the limitations it puts on the ability of the tank to quickly fire upon spotted enemies. Additionally, if the mounted individuals are not aware of where they are positioning themselves, they can often block the driver's view. As a result, this tactic was not often seen used by operators of the KSM1 tank. Strategic Contrary to the tactical mobility inherent to the tank itself and how it navigates the battlefield, srategic mobility is the ability of multiple vehicles to arrive in a timely, cost-effective, and synchronized fashion. For the Sironan Militia, this wasn't a major concern due to the nature of the force, with a focus more on quick but local defensive reactions. As such, the inherent mobility of the KSM1 proved effective enough to get the tanks into positions to respond to advancing threats within the standards expected of militia readiness. For the UNSC, however, the few KSM1s that they operated received slight modifications to address apparent deficiencies in strategic mobility of the vehicle compared to the Scorpion. Particularly, while the vehicle was smaller and lighter than the Scorpion, considerations had not been made for air-lift capabilities. As such, production KSM1 tanks, in both the original and A2 configurations, lacked attachment points to allow UNSC dropships, such as the Pelican, to carry the vehicle beneath their tails. Additionally, the Jabber lacked compatible points to which clamps could attach to the floors of UNSC frigate vehicle for atmospheric deployments. Both of these features were easily added, however, to UNSC models and few other changes proved necessary, with the size and weight remaining within the confines of what the UNSC was capable of transporting effectively. However, for a significant portion of original KSM1 tanks on Sirona, particularly those on the capital island, both militia and UNSC operated, saw the addition of attachment points for an amphibious conversion system. This was a temporary air cushion and propellor/rudder system that could be attached to the outside of the tank to allow it to deploy from Wet Fleet landing craft without submitting the landing craft themselves to shore-based fire. This system was later discontinued for the KSM1A2 after the Siege of Sirona proved that such amphibious capable craft proved less effective than simply transporting the vehicles over bodies of water through air-lifting them with Pelicans. Another factor in this decision was that Sironan Militia Jabbers saw minimal movement between theaters during the siege, typically remaining to defend their original position as per the doctrine of the militia as a local defensive supplement to the more mobile UNSC.